The Member of the British Empire (MBE) was unearthed in a vault in a cellar at London's St. James' Palace, where it was kept in its presentation box alongside a letter written by John when he returned it.

The letter says: "Your Majesty, I am returning my MBE as a protest against Britain's involvement in the Nigeria-Biafra thing, against our support of America in Vietnam and against 'Cold Turkey' slipping down the charts."

"Cold Turkey" was a song John performed with the Plastic Ono Band. The singer claimed he had never wanted his MBE but had been forced to accept it by the band's manager Brian Epstein.

After deciding to return it, he got his chauffeur Les Anthony to deliver it to Buckingham Palace.

The Beatles were awarded MBEs in 1965, but John decided to give his back four years later.

Fans of the band are urging John's widow Yoko Ono to reclaim the accolade.

Beatles Appreciation Society founder Gene Grimes said: "It should not be left to gather dust."

A palace spokesman said yesterday: "John Lennon's MBE is being taken good care of and is in storage at the Central Chancery. It has been retained since the day Mr. Lennon returned it, but in order to decide whether the medal could go on display in a museum, we would have to establish ownership first. It could be up to Yoko Ono as she is the custodian of John Lennon's estate."